load_balancer.h

/* Copyright 2021 <Madalina-Valentina Zanficu 313CA> */
#ifndef LOAD_BALANCER_H_
#define LOAD_BALANCER_H_

#include "CircularDoublyLinkedList.h"
#include "server.h"

// implemented my load_balancer with a circular doubly linked list
struct load_balancer {
	doubly_linked_list_t *hash_ring;
};
typedef struct load_balancer load_balancer;

// the elements that I stocked in the hash_ring
struct hr_element {
	unsigned int hash;
	int server_tag;
	int server_id;
	// pointer to hashtable
	server_memory* pServer;
};
typedef struct hr_element hr_element;

load_balancer* init_load_balancer();

void free_load_balancer(load_balancer* main);

/**
 * load_store() - Stores the key-value pair inside the system.
 * @arg1: Load balancer which distributes the work.
 * @arg2: Key represented as a string.
 * @arg3: Value represented as a string.
 * @arg4: This function will RETURN via this parameter
 *        the server ID which stores the object.
 *
 * The load balancer will use Consistent Hashing to distribute the
 * load across the servers. The chosen server ID will be returned
 * using the last parameter.
 */
void loader_store(load_balancer* main, char* key, char* value, int* server_id);

/**
 * load_retrieve() - Gets a value associated with the key.
 * @arg1: Load balancer which distributes the work.
 * @arg2: Key represented as a string.
 * @arg3: This function will RETURN the server ID
		  which stores the value via this parameter.
 *
 * The load balancer will search for the server which should posess the
 * value associated to the key. The server will return NULL in case
 * the key does NOT exist in the system.
 */
char* loader_retrieve(load_balancer* main, char* key, int* server_id);

/**
 * load_add_server() - Adds a new server to the system.
 * @arg1: Load balancer which distributes the work.
 * @arg2: ID of the new server.
 *
 * The load balancer will generate 3 replica TAGs and it will
 * place them inside the hash ring. The neighbor servers will
 * distribute some the objects to the added server.
 */
void loader_add_server(load_balancer* main, int server_id);

/**
 * load_remove_server() - Removes a specific server from the system.
 * @arg1: Load balancer which distributes the work.
 * @arg2: ID of the removed server.
 *
 * The load balancer will distribute ALL objects stored on the
 * removed server and will delete ALL replicas from the hash ring.
 */
void loader_remove_server(load_balancer* main, int server_id);

#endif  // LOAD_BALANCER_H_